Costocondritis is usually endemic, it is not usually having any cause, so as to y it started.
Seeing your symptoms I see you have more of gastritis also. And tats the major thing.
Do you have irregular food timings, lots of spicy things etc?
Next Steps
look for ur food hyegine, like timing and content of food, also noticewen does pain start _ before or after food.
medication and consult if u have already tried this